The present invention is directed to a head suspension for supporting a head slider relative to a rotating disk in a rigid disk drive, and in particular, to a head suspension having a shock limiter integrally formed in the load beam.
In a dynamic rigid disk storage device, a rotating disk is employed to store information. Rigid disk storage devices typically include a frame to provide attachment points and orientation for other components, and a spindle motor mounted to the frame for rotating the disk. A read/write head is formed on a xe2x80x9chead sliderxe2x80x9d for writing and reading data to and from the disk surface. The head slider is supported and properly oriented in relationship to the disk by a head suspension that provides both the force and compliance necessary for proper head slider operation. As the disk in the storage device rotates beneath the head slider and head suspension, the air above the disk also rotates, thus creating an air bearing which acts with an aerodynamic design of the head slider to create a lift force on the head slider. The lift force is counteracted by a spring force of the head suspension, thus positioning the head slider at a desired height and alignment above the disk which is referred to as the xe2x80x9cfly height.xe2x80x9d
Head suspensions for rigid disk drives include a load beam and a flexure. The load beam includes a mounting region at its proximal end for mounting the head suspension to an actuator of the disk drive, a rigid region, and a spring region between the mounting region and the rigid region for providing a spring force to counteract the aerodynamic lift force generated on the head slider during the drive operation as described above. The flexure typically includes a gimbal region having a slider mounting surface where the head slider is mounted. The gimbal region is resiliently moveable with respect to the remainder of the flexure in response to the aerodynamic forces generated by the air bearing. The gimbal region permits the head slider to move in pitch and roll directions and to follow disk surface fluctuations.
In one type of head suspension the flexure is formed as a separate piece having a load beam mounting region which is rigidly mounted to the distal end of the load beam using conventional methods such as spot welds. Head suspensions of this type typically include a load point dimple formed in either the load beam or the gimbal region of the flexure. The load point dimple transfers portions of the load generated by the spring region of the load beam to the flexure, provides clearance between the flexure and the load beam, and serves as a point about which the head slider can gimbal in pitch and roll directions to follow fluctuations in the disk surface.
As disk drives are designed having smaller disks, closer spacing, and increased storage densities, smaller and thinner head suspensions are required. These smaller and thinner head suspensions are susceptible to damage if the disk drive is subjected to a shock load or if the suspension experiences excessive pitch and roll motion. Moreover, as the use of portable personal computers increases, it is more likely that head suspensions in these portable computers will be subjected to shock loads. Thus, it is becoming increasingly important to design the head suspension so that it is less susceptible to excessive movements caused by shock loads and by pitch and roll motion, while still maintaining the necessary freedom of movement in the pitch and roll directions. In this manner, damaging contact between the head slider and the disk surface and permanent deformation of components of the head suspension can be prevented.
Mechanisms have been developed for limiting the movement of a free end of a cantilever portion of a flexure for protection against damage under shock loads. One such mechanism is disclosed in U.S. Pat. No. 4,724,500 to Dalziel. The Dalziel reference describes a limiter structure comprising a head slider having raised shoulders to which one or more elements are secured. The elements on the head slider overlap at least a portion of a top surface of the load beam to which the flexure is attached.
Another motion limiter is disclosed in U.S. Pat. No. 5,333,085 to Prentice et al. The head suspension shown in Prentice includes a tab that extends from a free end of a cantilever portion of a flexure. The tab is fitted through an opening of the load beam to oppose the top surface of the load beam.
Another motion limiter is disclosed in U.S. Pat. No. 5,526,205 to Aoyagi et al. The Aoyagi reference discloses a head suspension having a perpendicular hook at an end of a flexure. The hook is shaped to engage a transverse appendage at the distal end of a load beam to prevent the end of the flexure from displacing vertically too great a distance from the load beam.
Yet another motion limiter is disclosed in U.S. Pat. No. 5,877,920 to Resh. The Resh reference discloses a head suspension assembly including a load beam, a recording head and a gimbal including a head mounting tab on which the recording head is mounted. A displacement limiter extends between the load beam and the gimbal for limiting vertical displacement of the gimbal in a direction toward the recording head relative to the load beam.
Additionally, mechanisms have been developed for limiting motion of the overall load beam relative to the disk. One such mechanism is shown in Japanese Patent No. 11-66766 to Kawazoe. The Kawazoe patent teaches a hard disk drive having a suspension including a lift prevention member formed in or attached to the mounting region of the load beam that prevents lifting of the flying head away from the hard disk due to an impact load. Another mechanism is shown in U.S. Pat. No. 5,808,837 to Norton. The Norton patent teaches a hard disk drive having a suspension arm and a separate limit stop to restrain movement of the suspension arm that is mounted adjacent the suspension arm. Other mechanisms for restraining suspension movement are shown in U.S. Pat. No. 5,936,804 to Riener et al., U.S. Pat. No. 5,926,347 to Kouhei et al., and U.S. Pat. No. 5,831,793 to Resh.
A need still exists, however, for an improved head suspension including a mechanism capable of limiting motion of the suspension away from the surface of the disk due to impact and shock loading. Such a mechanism should work within the requirements of hard disk drive suspensions, including overall weight limitations, height limitations, manufacturability and functionality.
The present invention meets the ongoing need for improved head suspensions by providing a head suspension that includes an integral shock limiter. The head suspension is typically formed from a flexure and a load beam that has a mounting region, a rigid region and a spring region located between the mounting and rigid regions. The load beam includes a shock limiter integrally formed within the spring region as a cantilevered portion surrounded by a spring aperture used for adjusting the spring stiffness of the spring region. The cantilevered portion is configured to overlap a portion of the head suspension, such as the flexure, a portion of the load beam or a base plate mounted to the load beam at the mounting region.
A bend or radius is typically formed into the spring region in order to bias the head suspension toward the disk surface. A cantilevered portion of the shock limiter is formed to allow for a pre-determined gap between the shock limiter and the overlapped portion of the head suspension, when the suspension is held in its operating position. This gap allows for slight movement vertically before the shock limiter is engaged. Upon movement of the head suspension away from the disk surface due to an impact load, the head suspension flexes about the spring region and the rigid region of the load beam moves away from the disk surface. As the head suspension moves farther away from the disk surface, the cantilevered portion contacts the overlapped portion of the head suspension, thereby arresting the movement of the head suspension and limiting damage to the disk drive. The cantilevered portion may be reconfigured by bending to achieve the overlap with the overlapped portion of the head suspension.
The present invention provides a head suspension including a shock limiter integrally formed in the spring region of the load beam for limiting movement of the head suspension away from the surface of the disk over which the head suspension is suspended. Use of such an integral shock limiter provides the advantage of simultaneous formation with a spring aperture used to adjust the stiffness of the spring region. In addition, such a shock limiter allows for minimization of weight and manufacturing steps by utilizing material and processes already present in the fabrication of the head suspension. Yet another benefit of the shock limiter of the present invention is the ability to minimize load loss due to back bending of the spring region radius formed to provide gram loading at the head slider to counteract aerodynamic lifting forces on the head slider. These numerous benefits, along with the function of the shock limiter, set the present invention apart as a significant improvement in head suspension design.